/*
type int
parse 'add 2 3' 5
parse 'sub 8 3' 5
noparse 'div 9 3' 'Word:*:0' 5
*/

S <- "add":Word a:Digit b:Digit { a + b }
   / "sub":Word a:Digit b:Digit { a - b }

Digit <- d:[0-9] " "* { ref_0(d) - '0' }

Word :: ref_t <- w:[a-z]+ " "+ -> w
